There have been known electrophotographic apparatuses such as printers where developing cartridges are detachably mounted. Such electrophotographic apparatuses have new/old detection mechanisms to determine information of a mounted cartridge.
For example, an electrophotographic apparatus includes an apparatus main body having an actuator and new/old detection sensor, and a photosensitive drum unit detachably mounted to the apparatus main body. The photosensitive drum unit includes a detection piece gear and an idle gear.
This electrophotographic apparatus operates such that a driving force is transmitted to the detection piece gear via the idle gear. This rotates the detection piece gear, so that an action-imparting piece interferes with an action-receiving piece of the actuator, and moves the actuator. The new/old sensor detection the movement of the actuator, and the electrophotographic apparatus determines information of the photosensitive drum unit.